The present invention relates to a spacer for guiding flowing medium, especially in apparatus for filtering and separating such flowing medium via reverse osmosis and ultrafiltration, with a filter element being disposed between each two spacers, which have an essentially disk-like configuration with a central hole, and about which the flowing medium flows.
A multi-part device for accommodating filter elements is known, for example, from the apparatus for separating and filtering flowing medium disclosed in German Offenlegungsschrift 33 27 431 Mohn et al dated Feb. 14, 1985 and corresponding to U.S. Pat. No. 4,698,154-Mohn et al dated Oct. 6, 1987, where each individual filter unit of a filter element stack that is assembled in any desired number, comprises a carrier plate, a guide plate, and a diaphragm that is disposed between these two plates. With this heretofore known apparatus, the periphery of the diaphragm is preferably glued or otherwise joined to the periphery of the carrier plate within the axial through-flow opening.
When talking about such a known compact construction of filter units to form a filter element stack, one refers to a so-called disk modulus, where due to the construction of the individual filter units, the disks have a relatively great inherent stability and are relatively resistant to pressure.
However, consideration can be given if so-called diaphragm pads are to be used in such an apparatus; with these diaphragm pads include two outer diaphragm sheets that are hermetically sealed to flowing medium on their outer edges consideration also can be given to where the filtrate flows, for example, to a hole disposed in the center of the diaphragm pad, and from there being suitably collected and discharged to a filtrate outlet. But heretofore known disk-like spacers are not suitable for cooperating with such diaphragm pads because with such known spacers the flowing medium does not flow about the actual filter element (diaphragm pad) to a sufficient extent. Due to the construction of the heretofore known spacers, a considerable partial pressure drop occurs between the inlet and outlet of the flowing medium in the apparatus. This is a drawback, especially for large filter element stacks, and limits the efficiency of the apparatus. The reason for this is essentially that the actual diaphragm is placed upon the carrier plate and the guide plate, so that the flowing medium, for example untreated water, is increasingly held back as it flows through the filter element stack. The result, as indicated above, is a significant drop in partial pressure between the inlet and the outlet for the flowing medium.
It is therefore an object of the present invention to provide a spacer that permits the flowing medium to flow well about the spacer itself, as well as about the filter element that is disposed upon the spacer and is, for example, in the form of a diaphragm pad, so that even with large filter element stacks, the partial pressure differentials of the flowing medium between the inlet and the outlet are held within acceptable limits, the flow of the flowing medium is optimized, and the filter element is accommodated in such a way as to be resistant to differential pressure.